JP-7856092-B2 - Acrylic rubber, rubber compositions, and rubber crosslinked products

Inventors

• 渋谷 政憲

Assignees

• 日本ゼオン株式会社

Dates

Publication Date

20260511

Application Date

20220311

Priority Date

20210323

Claims (5)

1. A monomer unit containing at least one crosslinkable group selected from the group consisting of carboxyl group-containing monomer units, halogen atom-containing monomer units, and epoxy group-containing monomer units, (Meth)acrylamide monomer units, Acrylic rubber containing (meth)acrylic acid ester monomer units , The (meth)acrylic acid ester monomer units include ethyl acrylate units and n-butyl acrylate units. Acrylic rubber having a content of the (meth)acrylamide monomer unit in the total monomer units of 0.2 to 17.5% by weight.
2. The acrylic rubber according to claim 1, wherein the content of the (meth)acrylamide monomer unit in the total monomer unit is 1 to 15% by weight.
3. The acrylic rubber according to claim 1 or 2, wherein the crosslinkable group-containing monomer unit is the carboxyl group-containing monomer unit.
4. A rubber composition containing a rubber component comprising acrylic rubber as described in any one of claims 1 to 3, and a crosslinking agent.
5. A crosslinked rubber product obtained by crosslinking the rubber composition described in claim 4.

Description

The present invention relates to acrylic rubber, rubber compositions, and rubber crosslinked products, and more particularly to acrylic rubber that can provide rubber crosslinked products with excellent processability and excellent elongation at break and tensile strength, and to rubber compositions and rubber crosslinked products obtained using such acrylic rubber. Acrylic rubber is a polymer whose main components are units derived from (meth)acrylic acid ester monomers, such as alkyl (meth)acrylate monomers and alkoxyalkyl (meth)acrylate monomers. It is generally known as a rubber with excellent heat resistance, oil resistance, and ozone resistance, and is widely used in fields such as automobiles. Such acrylic rubber is typically produced by emulsion polymerization of monomer components mainly consisting of (meth)acrylic acid ester monomers, such as alkyl (meth)acrylate monomers or alkoxyalkyl (meth)acrylate monomers, adding a coagulant to the resulting emulsion polymerization solution to solidify it, and then drying the resulting hydrated crumb (see, for example, Patent Document 1). Japanese Unexamined Patent Publication No. 7-145291 <Acrylic rubber> The acrylic rubber of the present invention is an acrylic rubber containing at least one crosslinkable group-containing monomer unit selected from the group consisting of carboxyl group-containing monomer units, halogen atom-containing monomer units, and epoxy group-containing monomer units, and (meth)acrylamide monomer units, wherein the content of the (meth)acrylamide monomer units in the total monomer units is in the range of 0.2 to 17.5% by weight. The acrylic rubber of the present invention is a rubbery polymer that contains (meth)acrylic acid ester monomers [meaning acrylic acid ester monomers and/or methacrylic acid ester monomers; hereinafter the same applies to (meth)acrylate, etc.] as the main component (preferably 30% by weight or more of the total monomer units constituting the acrylic rubber) in its molecule. The (meth)acrylic acid ester monomers that form the (meth)acrylic acid ester monomer units, which are the main components of the acrylic rubber of the present invention, are not particularly limited, but examples include alkyl (meth)acrylic acid ester monomers and alkoxyalkyl (meth)acrylic acid ester monomers. The alkyl (meth)acrylate monomer is not particularly limited, but an ester of an alkanol having 1 to 12 carbon atoms and (meth)acrylic acid (a (meth)acrylic acid ester having an alkyl group having 1 to 12 carbon atoms) is preferred, an ester of an alkanol having 1 to 8 carbon atoms and (meth)acrylic acid (a (meth)acrylic acid ester having an alkyl group having 1 to 8 carbon atoms) is more preferred, and an ester of an alkanol having 2 to 6 carbon atoms and (meth)acrylic acid (a (meth)acrylic acid ester having an alkyl group having 2 to 6 carbon atoms) is even more preferred. Specific examples of alkyl (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate. Among these, ethyl (meth)acrylate and n-butyl (meth)acrylate are preferred, and ethyl acrylate and n-butyl acrylate are more preferred. These can be used individually or in combination of two or more. In particular, it is preferable to use ethyl acrylate and n-butyl acrylate in combination, and the weight ratio of "ethyl acrylate units: n-butyl acrylate units" is preferably 20:80 to 80:20, and more preferably 40:60 to 60:40. The (meth)acrylate alkoxyalkyl ester monomer is not particularly limited, but an ester of an alkoxyalkyl alcohol having 2 to 12 carbon atoms and (meth)acrylic acid (a (meth)acrylic acid ester having an alkoxyalkyl group having 2 to 12 carbon atoms) is preferred, an ester of an alkoxyalkyl alcohol having 2 to 8 carbon atoms and (meth)acrylic acid (a (meth)acrylic acid ester having an alkoxyalkyl group having 2 to 8 carbon atoms) is more preferred, and an ester of an alkoxyalkyl alcohol having 2 to 6 carbon atoms and (meth)acrylic acid (a (meth)acrylic acid ester having an alkoxyalkyl group having 2 to 6 carbon atoms) is even more preferred. Specific examples of (meth)acrylate alkoxyalkyl ester monomers include methoxymethyl (meth)acrylate, ethoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-propoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, and 4-methoxybutyl (meth)acrylate. Among these, 2-ethoxyethyl (meth)acrylate and 2-methoxyethyl (meth)acrylate are preferred, and 2-ethoxyethyl acrylate and 2-methoxyethyl acrylate are particularly preferred. These can be used individually or in combination of two or more. The content of (meth)acrylic acid ester monomer units in the total monomer units constituting the acrylic rubber of the present invention is preferably 50% by weight or more, m